Rekor is a software supply chain transparency log

Overview

Rekor is a software supply chain transparency log. Starting in version 0.3.0 and prior to version 1.5.2, the Package.Unmarshal() function in pkg/types/alpine/apk.go decompresses the signature and control gzip members of an APK file into in-memory buffers without bounding the total decompressed size. The existing max_apk_metadata_size check (default 1MB) is only applied to individual tar entry header sizes after decompression completes, so it does not prevent a decompression bomb from consuming unbounded heap memory. An attacker can craft a gzip stream that compresses at a ~1000:1 ratio (e.g., 2MB compressed zeros → 2GB decompressed). When submitted as spec.package.content in an Alpine ProposedEntry, the server decompresses the full payload into memory during request processing, triggering a fatal Go runtime out-of-memory error or OS OOM-kill that cannot be caught by the server's recover() middleware. This is reachable via two unauthenticated endpoints, POST /api/v1/log/entries (createLogEntry) and POST /api/v1/log/entries/retrieve (searchLogQuery). Both invoke V001Entry.Canonicalize() → fetchExternalEntities() → apk.Unmarshal(packageData), which performs the unbounded decompression. Version 1.5.2 patches the issue. There is no effective workaround. Setting max_request_body_size reduces but does not eliminate exposure due to the ~1000:1 compression ratio (a 1MB body limit still allows ~1GB heap allocation). Setting max_apk_metadata_size has no effect on this vulnerability since the check is applied after decompression.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

Package advisory (CVE-2026-48702)

Affected packages:

• github.com/sigstore/rekor >= 0.3.0, < 1.5.2

Patched in:

• github.com/sigstore/rekor 1.5.2

Source: https://osv.dev/vulnerability/GHSA-47q9-m4ww-924m

Vendor advisories

• RHSA-2026:25138 · Red Hat · fixed in: Red Hat Hardened Images · released 2026-06-10 · advisory
• RHSA-2026:35111 · Red Hat · fixed in: Red Hat Hardened Images · released 2026-07-02 · advisory
• RHSA-2026:59439 · Red Hat · fixed in: Red Hat Trusted Artifact Signer 1.3 · released 2026-08-25 · advisory
• RHSA-2026:50873 · Red Hat · fixed in: Red Hat Trusted Artifact Signer 1.4 · released 2026-08-05 · advisory
• Red Hat VEX · Important · affected: Multicluster Engine for Kubernetes, Red Hat Trusted Artifact Signer · no fix planned: Multicluster Engine for Kubernetes, Red Hat Trusted Artifact Signer · updated 2026-09-14 · vex